The present invention relates to articles of footwear, and in particular, to those including spring elements, and to footwear constructions which include selectively removable and renewable components.
The article of footwear taught in the present invention includes a spring element which can provide improved cushioning, stability, running economy, and a long service life. Unlike the conventional foam materials presently being used by the footwear industry, the spring element is not substantially subject to compression set degradation and can provide a relatively long service life. The components of the article of footwear including the upper, insole, spring element, and outsole portions can be selected from a range of options, and can be easily removed and replaced, as desired. Further, the relative configuration and functional relationship as between the forefoot, midfoot and rearfoot areas of the article of footwear can be readily modified and adjusted. Accordingly, the article of footwear can be customized by a wearer or specially configured for a select target population in order to optimize desired performance criteria.
Conventional athletic footwear typically include an outsole made of a rubber compound which is affixed by adhesive to a midsole made of ethylene vinyl acetate or polyurethane foam material which is in turn affixed by adhesive to an upper which is constructed with the use of stitching and adhesives. Because of the difficulty, time, and expense associated with renewing any portion of conventional articles of footwear, the vast majority are generally discarded at the end of their service life. This service life can be characterized as having a short duration when the wearer frequently engages in athletic activity such as distance running or tennis. In tennis, portions of the outsole can be substantially abraded within a few hours, and in distance running the foam midsole can become compacted and degrade by taking a compression set within one hundred miles of use. The resulting deformation of the foam midsole can degrade cushioning, footwear stability, and contribute to athletic injuries. Accordingly, many competitive distance runners who routinely cover one hundred miles in a week""s time will discard their athletic footwear after logging three hundred miles in order to avoid possible injury.
Even though the service life of conventional athletic footwear is relatively short, the price of athletic footwear has steadily increased: over the last three decades, and some models now bear retail prices over one hundred and twenty dollars. However, some of this increase in retail prices has been design and fashion driven as opposed to reflecting actual value added, thus some individuals believe that the best values on functional athletic footwear can be found in the price range of fifty to eighty dollars. In any case, conventional athletic footwear remain disposable commodities and few are being recycled. The method of manufacture and disposal of conventional athletic footwear is therefore relatively inefficient and not environmentally friendly.
In contrast with conventional athletic footwear, the present invention teaches an article of footwear that includes spring elements which do not take a compression set or similarly degrade, thus the physical and mechanical properties afforded by a preferred article of footwear remain substantially the same over a useful service life which can be several times longer than that of conventional articles footwear. The present invention teaches an article of footwear which represents an investment, as opposed to a disposable commodity. Like an automobile, the preferred article of footwear includes components which can be easily renewed and replaced, but also components which can be varied and customized, as desired.
Prior art examples devices and means for selectively and removably affixing various components of an article of footwear include, e.g., U.S. Pat. No. 2,183,277, U.S. Pat. No. 2,200,080, U.S. Pat. No. 2,552,943, U.S. Pat. No. 2,640,283, U.S. Pat. No. 3,818,617, U.S. Pat. No. 3,878,626, U.S. Pat. No. 3,906,646, U.S. Pat. No. 3,982,336, U.S. Pat. No. 4,103,440, U.S. Pat. No. 4,262,434, U.S. Pat. No. 4,267,650, U.S. Pat. No. 4,279,083, U.S. Pat. No. 4,300,294, U.S. Pat. No. 4,317,294, U.S. Pat. No. 4,351,120, U.S. Pat. No. 4,377,042, U.S. Pat. No. 4,606,139, U.S. Pat. No. 4,807,372, U.S. Pat. No. 4,887,369, U.S. Pat. No. 5,083,385, U.S. Pat. No. 5,317,822, U.S. Pat. No. 5,410,821, U.S. Pat. No. 5,533,280, U.S. Pat. No. 5,542,198, U.S. Pat. No. 5,615,497, U.S. Pat. No. 5,644,857, U.S. Pat. No. 5,657,558, U.S. Pat. No. 5,661,915, and U.S. Pat. No. 5,826,352.
Conventional athletic footwear cannot be substantially customized for use by the consumer or wearer. The physical and mechanical properties of conventional athletic footwear are relatively fixed generic qualities. However, the body weight or mass and characteristic running technique of different individuals having the same footwear size can vary greatly. Often, the stiffness in compression of the foam material used in the midsole of athletic shoes can be too soft for individuals who employ more forceful movements, or who have greater body mass than, an average wearer. Accordingly, conventional articles of athletic footwear do not provide. optimal performance characteristics for individual wearers.
In contrast, the present invention permits a wearer to customize a preferred article of footwear. For example, the length, width, girth, and configuration of the upper, as provided by various last options, or by two or three dimensional modeling and footwear design equipment such as computer software, or by two, three, or four dimensional measurement devices such as scanners, as well as the type of footwear construction and design of the upper can be selected by the consumer or wearer. Further, the physical and mechanical properties of the article of footwear can be selected and changed as desired in order to optimize desired performance characteristics given various performance criteria or environmental conditions. For example, the configuration and geometry of the article of footwear, and the stiffness of the spring elements can be customized, as desired. In addition, the ability to easily remove, renew, and recycle the outsole portions of the preferred article of footwear renders the use of softer materials having enhanced shock and vibration dampening characteristics, but perhaps diminished wear properties viable from a practical standpoint. Moreover, the outsole portion of the preferred article of. footwear can be selected from a variety of options with regards to configuration, materials, and function.
The physical and mechanical properties associated with an article of footwear of the present invention can provide enhanced cushioning, stability, and running economy relative to conventional articles of footwear. The spring to dampening ratio of conventional articles of footwear is commonly in the range between 40-60 percent, whereas the preferred article of footwear can provide a higher spring to dampening ratio, thus greater mechanical efficiency and running economy. The preferred article of footwear can include an anterior spring element that underlies the forefoot area which can store energy during the latter portion of the stance phase and early portion of the propulsive phase of the running cycle, and then release this energy during the latter portion of the propulsive phase, thus facilitating improved running economy. It is believed that the resulting improvement in running performance can approximate one second over four hundred meters, or two to three percent.
The preferred article of footwear can provide differential stiffness in the rearfoot area so as to reduce both the rate and magnitude of pronation, or alternately, the rate and magnitude of supination experienced by an individual wearer, thus avoid conditions which can be associated with injury. Likewise, the preferred article of footwear can provide. differential stiffness in the midfoot and forefoot areas so as to reduce both the rate and magnitude of inward and/or outward rotation of the foot, thus avoid conditions which can be associated with injury. The preferred spring elements can also provide a stable platform which can prevent or reduce the amount of deformation caused by point loads, thus avoid conditions which can be associated with injury.
Again, the viability of using relatively soft outsole materials having improved shock and vibration dampening characteristics can enhance cushioning effects. Further, in conventional articles of footwear, the shock and vibration generated during rearfoot impact is commonly transmitted most rapidly to a wearer through that portion of the outsole and midsole which has greatest stiffness, and normally, this is a portion of the sole proximate the heel of the wearer which undergoes the greatest deflection and deformation. However, in the present invention a void space exists beneath the heel of a wearer and the ground engaging portion of the outsole. Some of the shock and vibration generated during the rearfoot impact of an outsole with the ground support surface must then travel a greater distance through the outsole and inferior. spring element in order to be transmitted to the superior spring element and a wearer. In addition, in the present invention, a posterior spacer which serves as a shock and vibration isolator, and also. vibration decay time modifiers can be used to decrease the magnitude of the shock and vibration transmitted to the wearer of a preferred article of footwear.
There have been many attempts in the prior art to introduce functional spring elements into articles of footwear including, but not limited to U.S. Pat. No. 357,062, U.S. Pat. No. 1,107,894, U.S. Pat. No. 1,113,266, U.S. Pat. No. 1,352,865, U.S. Pat. No. 1,370,212, U.S. Pat. No. 2,447,603, U.S. Pat. No. 2,508,318, U.S. Pat. No. 4,429,474, U.S. Pat. No. 4,492,046, U.S. Pat. No. 4,314,413, U.S. Pat. No. 4,486,964, U.S. Pat. No. 4,506,460, U.S. Pat. No. 4,566,206, U.S. Pat. No. 4,771,554, U.S. Pat. No. 4,854,057, U.S. Pat. No. 4,878,300, U.S. Pat. No. 4,942,677, U.S. Pat. No. 5,052,130, U.S. Pat. No. 5,060,401, U.S. Pat. No. 5,138,776, U.S. Pat. No. 5,159,767, U.S. Pat. No. 5,203,095, U.S. Pat. No. 5,279,051, U.S. Pat. No. 5,337,492, U.S. Pat. No. 5,343,639, U.S. Pat. No. 5,353,523, U.S. Pat. No. 5,367,790, U.S. Pat. No. 5,381,608, U.S. Pat. No. 5,437,110, U.S. Pat. No. 5,461,800, U.S. Pat. No. 5,596,819, U.S. Pat. No. 5,701,686, U.S. Pat. No. 5,822,886, U.S. Pat. No. 5,875,567, U.S. Pat. No. 5,937,544, and, 6,029,374, all of these patents hereby being incorporated by reference herein. Relatively few of these attempts have resulted in functional articles of footwear which have met with commercial success. The limitations of some of the prior art has concerned the difficulty of meeting the potentially competing criteria associated with cushioning and footwear stability. In other cases, the manufacturing costs of making prior art articles of footwear including spring elements have proved prohibitive.
The present invention teaches an article of footwear which can provide a wearer with improved cushioning and stability, running economy, and an extended service life while reducing the risks of injury normally associated with footwear degradation. The preferred article of footwear provides a wearer with the ability to customize the fit, but also the physical and mechanical properties and performance of the article of footwear. Moreover, the preferred article of footwear is economical and environmentally friendly to both manufacture and recycle.
A preferred article of footwear has an anterior side, posterior side, medial side, lateral side, longitudinal axis transverse axis and includes an upper, and a spring element including a superior spring element, and an inferior spring element. The inferior spring element is affixed in function relation to the superior spring element and projects rearward and downward therefrom, and has an flexural axis deviated from the transverse axis in the range between 10 and 50 degrees.
It can be advantageous for the flexural axis to be deviated from the transverse axis in the range between 10 and 30 degrees in articles of footwear intended for walking, or for use by runners who tend to supinate during the braking and stance phases of the running cycle, and in the range between 30 and 50 degrees for runners who tend to pronate during the braking and stance phases of the running cycle. Accordingly, posterior oft he flexural axis, the anterior to posterior lengths of the superior spring element and the inferior spring element can be shorter on the medial side than on the lateral side.
The preferred article of footwear includes a spring element having a superior spring element which can be formed in a shape substantially corresponding to the footwear last bottom, and an inferior spring element. The superior spring element can consist of a single component, or can consist of two portions, an anterior spring element and a posterior spring element which are affixed together in functional relation. In an alternate embodiment, the anterior spring element and inferior spring element can consist of a single component, or alternately, can be affixed together in functional relation, and the posterior spring element can be affixed in functional relation thereto. Further, it can be readily understood that an equivalent spring element can be formed as a single part, or in four parts.
The superior spring element can be positioned in functional relation within the upper and the outsole can be positioned inferior to the upper, and a plurality of fasteners can be used for affixing the superior spring element to the outsole, thus trapping and securing the upper in functional relation therebetween. Further, a plurality of fasteners can be used to selectively affix the superior spring element in functional relation to the upper and the inferior spring element. The upper can further include a sleeve for affixing at least a portion of the superior spring element in function relation thereto.
The superior spring element and inferior spring element can be configured or affixed in functional relation to form a v-shape in the rearfoot area of an article of footwear and provide deflection in the range between 8-15 mm, and preferrably approximately 10 mm.
At the posterior side, the v-shaped spring element can exhibit less stiffness in compression on the lateral side relative to the medial side, and it can be advantageous that the differential stiffness be in the range between two-to-three to one.
The superior spring element can have a thickness in the range between 1.0 and 3.5 mm. The superior spring element can include an anterior spring element having a thickness in the range between 1.0-2.0 mm, and a posterior spring element having a thickness in the range between 2.0 and 3.5 mm. The inferior spring element can have a thickness in the range between 2.0 and 3.5 mm.
The posterior spring element can further include a projection, and the anterior spring element and posterior spring element can be. affixed by at least three fasteners in triangulation.
The superior spring element can be generally planar, or alternately can be curved to mate with the anatomy of a wearer and further include elevated portions such as a side stabilizer or a heel counter.
The spring element can be made of a fiber composite material, or alternately, a thermoplastic material, or a metal material. The spring element can include areas having different thickness, notches, slits, or openings which serve to produce differential stiffness when the spring element is loaded. The spring element can include different types, orientations, configurations, and numbers of composite layers, and in different areas, in order to achieve differential stiffness when the spring element is loaded. Accordingly, the flexural modulus or stiffness exhibited by a spring element in the rearfoot, midfoot, and forefoot areas, and about any axis can be engineered, as desired.
The article of footwear can include a selectively removable outsole. The outsole can include an anterior outsole element and posterior outsole element. Alternately, the outsole can consist of a single component, or a three part component including an anterior outsole element, a middle outsole element and a posterior outsole element. The outsole can include a backing, a tread or ground engaging surface, and lines of flexion.
The article of footwear can further include a spring guard for protecting the posterior aspect of the mating portions of the superior spring element or posterior spring element and the inferior spring element.
The article of footwear can further include, an anterior spacer positioned between the anterior spring element and the posterior spring element for dampening shock and vibration. The anterior spacer can have a wedge shape which can be used to modify the configuration and performance of the article of footwear.
The article of footwear can further include a posterior spacer positioned between the superior spring element or posterior spring element and the inferior spring element for dampening shock and vibration. The posterior spacer can have a wedge shape which can be used to modify the configuration and performance of the article of footwear.
The article of footwear can further include a vibration decay time modifier. The vibration decay time modifiers can include a head and a stem. The head of the vibration decay time modifiers can be dimensioned and configured for vibration substantially free of contact with the base of the posterior spacer or spring element in directions which substantially encompass a 360 degree arc and normal to the longitudinal axis of the stem.
A preferred article of footwear can include an anterior side, posterior side, medial side, lateral side, and an upper affixed in functional relation to a spring element comprising an anterior spring element, a posterior spring element, and an inferior spring element. The anterior spring element can be affixed in functional relation to the posterior spring element, and a substantial portion of the anterior spring element can extend anterior of a position associated with 70 percent of the length of the upper as measured from the posterior side. The inferior spring element can be affixed in function relation to the posterior spring element, and a substantial portion of the inferior spring element can extend posterior of a position associated with 50 percent of the length of the upper as measured from the posterior side.
In an alternate embodiment of an article of footwear, the spring element can consist of a superior spring element which can include an anterior spring element and a posterior spring element affixed together in functional relation, but not include an inferior spring element projecting rearward and downward therefrom.
The ability to easily customize and adapt the preferred article of footwear in a desired manner can render the present invention suitable for use in walking, running, and a variety of other athletic activities including tennis, basketball, baseball, football, soccer, bicycling, and in-line skating.